Endotracheal intubation is a routine life preserving procedure with application in a vast number of settings. Situations in which a patient's airway needs to be secured with an endotracheal tube are numerous and include tracheal intubation in a patient when undergoing a general anesthetic or when the patient requires prolonged treatment in an intensive care unit or is subjected to a field emergency where the patient's status may need to be further clarified in the hospital.
A secure, reliable airway for the patient is of paramount importance. A patient who requires ventilatory support for survival is dependent on the timely and accurate placement of an endotracheal tube within his or her trachea. Safe and expedient endotracheal tube placement is therefore of the highest priority both in the operating room as well as other settings in which the patient is unable to adequately oxygenate and ventilate.
With that goal in mind, the American Society of Anesthesiology (ASA) has undertaken research and educational efforts to promote safe endotracheal intubation. The much-cited ASA “Closed Claims” study revealed the serious consequences of the inability to secure a patient's airway. Indeed, the study showed that nearly 17% of all claims against anesthesiologists were due to “difficult” intubations. Distressingly, since 1992, up to one third of all anesthesia related deaths during operating procedures have been due to failed intubations.
During the routine intubation of an otherwise healthy individual, the practitioner has the relative comfort of time on his or her side. The patient is initially examined and a pre-intubation assessment of difficulty is made with regard to intubation. If the patient's clinical airway assessment is unremarkable, pre-oxygenation is carried out, anesthetic medications are administered and then mask ventilation of the patient is initiated. Assuming the patient is easily ventilated, the practitioner proceeds with administering a muscle relaxant and then proceeds with direct laryngoscopy and endotracheal tube placement.
Unfortunately, not all tracheal intubations proceed as smoothly as the above description. In fact, approximately 3-18% of all intubations carried out under routine anesthesia can be classified as “difficult” intubations. A difficult intubation has been defined as one in which three attempts by an experienced practitioner fails to yield successful placement of an endotracheal tube. While the pre-operative examination can offer important indications as to a possible difficult intubation, factors such as neck size, Mallampati view, neck extension, and mouth opening are only partially predictive of a difficult intubation. Therefore, the very real possibility of the dreaded unknown/unanticipated difficult airway is a situation in which every practitioner must be able to successfully handle.
In the foregoing scenario, the proficient, reproducible use of the non-direct laryngoscopic technique is paramount. One particular type of non-direct laryngoscopic technique utilizes a video laryngoscope, such as the GlideScope produced by the Saturn Biomedical System, Inc., Bumaby, British Columbia, Canada. This device has been shown by multiple studies to provide improved glottic views (Cormack-Lehane) in both simulated easy and difficult airways when compared to the use of Macintosh (direct) laryngoscopy. A commonly cited difficulty in the successful use of the GlideScope is in timely and efficient placement of the endotracheal tube once the glottis has been visualized. One method for successful intubation, as stated in the literature and advised by the manufacturer, recommends that the styletted endotracheal tube have an angulated tip so as to match the 60 degree angulation of the GlideScope blade. An alternate method utilizes a styletted endotracheal tube in the shape of an “L” or commonly known as a “hockey stick”. In many instances of difficult intubation with the videolaryngoscope, the primary obstacle is not visualization of the glottic anatomy, but rather the difficulty in successfully placing the endotracheal tube through the vocal cords. A commonly encountered difficulty in this respect is the positioning of the endotracheal tube tip in the vertical plane just prior to passing it through the vocal cords. Another common difficulty is the inability to advance the endotracheal tube through the vocal cords and into the trachea. Thus, the overall configuration of the endotracheal tube is of paramount importance in obtaining a successful intubation.
Historically, when a stylette is used to facilitate intubation, the styletted endotracheal tube is formed into the aforementioned “hockey stick” configuration. However, this shape is fundamentally flawed for positioning of the distal end of the endotracheal tube through the vocal cords. Although the tip of the endotracheal tube may finally be maneuvered to the vocal cords, it is common for the practitioner to have difficulty advancing the endotracheal tube through the vocal cords and into the trachea due to the “L shaped” bend involved causing the tip of the endotracheal tube to drag or stick on the anterior rings of the trachea. This “hockey stick” configuration also results in the common occurrence of inadvertent extubation (endotracheal tube falling out of the patient's trachea) upon the withdrawal of the stylette from the lumen of the endotracheal tube.
Various patents have been directed to forming the configuration of the endotracheal tube to assist in the intubation process. For example, the Gomez reference (U.S. Pat. No. 6,053,166) is directed to an intubation assembly having a guide assembly that receives the intubation tube therein and conforms the configuration of the intubation tube. The guide assembly includes a first segment and a second segment that are hingedly coupled to one another and positionable between a closed position which defines a curved configuration of the guide assembly and an open position which defines a straight configuration of the guide assembly.
The Schwartz reference (U.S. Pat. No. 6,539,942) discloses a device for facilitating intubation comprising a tube that is inserted into an endotracheal tube. The device includes a control wire and handgrip to curve the distal end of the device into the desired configuration via a series of interlinked, ring-like elements disposed along the distal end of the tube. The amount of force applied to the handgrip controls the degree of bend achieved in the distal end of the device.
The Toti, et. al. reference (U.S. Pat. No. 6,321,749) discloses an endotracheal tube having a portion thereof that can be bent during intubation so as to control the position of the distal end of the tube. The distal end of the endotracheal tube is configured by means of a wire which is received within the endotracheal tube and which can be pulled causing the distal end of the tube to be curved or bent for placement in the trachea of the person being intubated.
The Raspallo reference (U.S. Pat. No. 6,874,504) discloses an endotracheal tube having a proximal tube shaft, which is coupled to a distal tube shaft. The distal tube shaft includes two or more curved portions configured to be inserted into the trachea when the tube is inserted into the person being intubated. An inflatable cuff covers at least a portion of the two or more curved portions of the distal end of the endotracheal tube.
The Parker reference (U.S. Pat. No. 5,174,283) discloses a guide member having a channel therein for the receipt of an orotracheal tube. The guide member is positioned atop the larynx such that the wall of the channel forms an upward continuation of the laryngeal wall. The orotracheal tube is advanced through the channel into the larynx and trachea preventing the accidental intubation of the esophagus.
All of the devices in the foregoing references are rather complex and, due to their structure and/or operation, have certain inherent operational disadvantages. Many of these devices cannot be used in conjunction with videolaryngoscopy due to the limited space in the patient's mouth. Thus, these devices cannot take advantage of an excellent proven means for visualizing the vocal cords. Also, many of these devices cannot be used in conjunction with routine direct laryngoscopy which is the standard method of endotracheal intubation. Many practitioners routinely use a styletted endotracheal tube with the fundamentally flawed “hockey stick” configuration due to the inability to reliably, easily and effectively reproduce other styletted endotracheal tube configurations. Ideally, the device should not only allow the formation of bends in the endotracheal tube but would also provide the ability to form readily reproducible curves given that the normal anatomy of the tongue is more curved than straight. Such curves would also provide additional desirable mechanical features not only for maneuvering the endotracheal tube in the patient's mouth, but also for advancing the tube through the vocal cords into the trachea. The styletted endotracheal tube, with curves therein, would also have a mechanical advantage of not extubating the trachea, as commonly occurs with the tube when in the “hockey stick” configuration. In contrast, due to the configuration of the formed endotracheal tube, withdrawal of the curved, formed stylette from the endotracheal tube causes the distal end of the endotracheal tube to advance further into the trachea of the patient being intubated.
With this in mind, it has become desirable to develop a mold (form) to reliably and easily configure a styletted endotracheal tube having bends and curves therein so as to assist the practitioner in the insertion of the distal end of same through the vocal cords and into the trachea of the patient during the intubation process. It is apparent from the foregoing that teaching the technique of intubation is difficult and standardizing a variable, such as forming the configuration of the endotracheal tube utilizing such a mold, will provide a faster learning curve for those being taught the technique of intubation.